1. Technical Field
The present invention generally relates to a liquid crystal display device, and more particularly, to a method of providing data capable of preventing motion blurring phenomenon, a liquid crystal display device and a driving method thereof.
2. Description of the Related Art
Generally, a liquid crystal display device (LCD) is a device for displaying an image using a principle that each pixel of a liquid crystal panel acts as an optical switch to selectively transmit a light generated from a light source. In comparing a related art cathode ray tube (CRT) with an LCD, the related art CRT controls brightness by adjusting the intensity of electron beam, whereas the LCD controls the brightness of image by adjusting the intensity of light generated from the light source.
Meanwhile, as the image technology has been developed more and more, a technology displaying a motion picture as well as a still picture can be embodied in the LCD.
However, it is not easy to implement a motion picture well in the LCD. That is, since the response speed of a liquid crystal is slower than a frame rate in the motion picture, there occurs a motion blurring when applying a voltage newly in a next frame after a predetermined voltage. For example, an image signal or a data voltage, previously charged at the liquid crystal, is maintained for one frame. The data of the previous frame has an effect on the data of the next frame, which becomes a cause of the motion blurring phenomenon.
In particular, this motion blurring phenomenon strongly occurs in displaying a motion picture rather than in displaying a still picture.
FIG. 1A is a graph illustrating a light intensity versus time in a related art CRT, and FIG. 1B is a graph illustrating a light intensity versus time in a related art LCD.
Referring to FIG. 1A, the CRT is driven by an impulse type. In this case, since the data is displayed for only an extremely short time of each frame period, the data displayed for only the extremely short time does not have an effect on a next frame period.
In comparison, referring to FIG. 1B, the LCD is driven by a hold type. Accordingly, the data is continuously maintained for each frame period so that the data maintained during a previous frame period has an effect on a next frame period. The motion blurring phenomenon inevitably occurs in the related art LCD which is driven by the hold type.
To prevent the motion blurring phenomenon, there has been proposed a black data insertion (BDI) method in which image data is applied only during a predetermined period of one frame period and a black data is applied during the other period of one frame period. Herein, the black data means the data voltage corresponding to a black gray scale, e.g., 0 gray scale. Therefore, a human eye never detects any brightness, i.e., for example the gray scale more than 0, because each pixel displays the black gray scale due to the black data.
FIG. 2 is a schematic view illustrating the BDI method in a related art LCD.
Referring to FIG. 2, the image data voltage and the black data voltage are alternately applied to a liquid crystal panel during one frame period.
If there exist 488 gate lines, for example, a first through a fifth gate lines are sequentially activated first so that an image data voltage is applied to pixels of each activated gate line. Thereafter, the first through the fifth gate lines are activated again so that the black data voltage is applied to the pixels of each activated gate line.
Subsequently, a sixth through a tenth gate lines are sequentially activated so that an image data voltage is applied to pixels of each activated gate line. Afterwards, the sixth through the tenth gate lines are activated again so that the black data voltage is applied to the pixels of each activated gate line.
Such an operation is performed repeatedly for one frame period in which 488 gate lines are activated.
Likewise, the same procedure is also performed during a next frame period.
In the related art LCD, a black data may be provided to a data driver after it may be generated in a timing controller. In this case, various circuits should be additionally employed for providing the black data generated by the timing controller to the liquid crystal panel via the data driver on an appropriate timing. As a result, the overall circuit becomes too complicated and too expensive.
In general, the LCD requires a predetermined frequency for activating each gate line one time within one frame period. However, as described above, since each gate line should be activated at least one time or more during the one frame period for applying the black data, the LCD using the BDI method requires higher driving frequency than the other LCDs, which complicates the design of a circuit for generating a high driving frequency. In addition, there may be a problem in that power consumption also increases, as the driving frequency increases. And the general black data insertion method has a dim line problem. There is a vertical blank period in the related LCD where no data is applied to the data lines and no gate scan pulse is applied to the gate lines. Because there is no data insertion during the vertical blank period, the data displayed on the LCD panel maintains a state of the beginning time of the vertical blank period. Therefore a boundary between the image data portions and the black data portions becomes more clear and the boundary is seen as a dim line problem. Because The boundary emerges at the same position at every frame and the liquid crystal has a sticky characteristic, the dim line becomes heavier.